Rapid colonization and biodegradation of untreated commercial polyethylene wrap by a new strain of Bacillus velezensis C5.

Biodegradation could be a potential alternative solution to polyethylene (PE) pollution. However, its hydrophobic surface and long carbon chains make extremely low biodegradation efficiency. In this study, we screened a novel potential bacterial strain C5 (CGMCC number: 1.18715) for low-density polyethylene (LDPE) biodegrading from landfills. The strain was identified as Bacillus velezensis according to its 16S rRNA sequence. The contact angle analysis indicated that C5 could rapidly form biofilm on untreated LDPE which resulted in contact angles decreasing from 100° to 54° over 7 d. After the LDPE film incubated with C5 for 90 d, the thickness and weight of LDPE film decreased by 26% and 8.01%, respectively. Besides, the biotreated PE film was found with increases in weight-averaged molecular weight by 29.8%, suggesting low molar mass chains were consumed. C24-C29 n-alkanes were detected in the biodegradation products, which proved the depolymerization of LDPE. Combined with the genome mining results, a possible biofilm-aided degrading mechanism was proposed and might involve key enzymes, such as laccase, cytochrome P450 and propionyl-CoA carboxylase, which could constitute a multienzyme system for the co-catalytic degradation of LDPE waste.

Role and influence of extracellular polymeric substances on the preparation of aerobic granular sludge.

Due to the important role of the extracellular polymeric substances in the formation of aerobic granular sludge, the variation of the EPS contents in the process of cultivation and that in the one running cycle time were studied in this work. Aerobic granules with diameters between 0.8 and 1.1 mm were obtained within 30-35 days. The results suggested that the increase of EPS contents significantly contributed to the formation of aerobic granules. A linear relationship between the EPS and SVI was also developed, and it revealed that the aerobic granules had good settling property when the EPS exceeded 200 mg/g MLVSS. Two mainly components of EPS, protein (PN) and polysaccharides (PS), could act as the endogenous food for the microbes during the starvation period. The survival of the microbial population was jeopardized when the F/M ration was below 0.5 g COD/g SS d.

Enhancing nitrogen removal performance using immobilized aerobic denitrifying bacteria by modified polyvinyl alcohol/sodium alginate (PVA/SA).

Aerobic denitrification has emerged as a promising and efficient method for nitrogen removal from wastewater. However, the direct application of aerobic denitrifying bacteria has faced challenges such as low nitrogen removal efficiency, bacterial loss, and poor stability. To address these issues, this study developed a novel microbial particle carrier using NaHCO3-modified polyvinyl alcohol (PVA)/sodium alginate (SA) gel (NaHCO3-PVA/SA). This carrier exhibits several advantageous properties, including excellent mass transfer efficiency, favorable biocompatibility, convenient film formation, abundant biomass, and exceptional pollutant treatment capacity. The carrier was modified with 0.3% NaHCO3, 8.0% PVA, and 1.0% SA, resulting in a remarkable 3.4-fold increase in the average pore diameter and a 12.8% improvement in mass transfer efficiency. This carrier was utilized to immobilize the aerobic denitrifying bacterium Stutzerimonas stutzeri W-2 to enhance nitrogen removal (NaHCO3-PVA/SA@W-2), resulting in a NO3--N removal efficiency of 99.06%, which was 21.39% higher than that without modification. Compared with the non-immobilized W-2, the degradation efficiency was improved by 43.70%. After five reuses, the NO3--N and TN removal rates remained at 99% and 93.01%, respectively. These results provide a solid foundation for the industrial application of the modified carrier as an effective tool for nitrogen removal in large-scale wastewater treatment processes.

Synergistic analysis of performance, microbial community, and metabolism in aerobic granular sludge under polyacrylonitrile microplastics stress.

Aerobic granular sludge (AGS) has proved to be a promising biotechnology for microplastics wastewater treatment. However, polyacrylonitrile microplastics (PAN MPs), the most widely used plastic in textile materials, have not been investigated. Therefore, the effect of the neglected PAN MPs on AGS at different concentrations (1, 10, and 100 mg/L) was evaluated. The results indicated that PAN MPs with 1 and 10 mg/L concentrations had no obvious effect on granular stability and nutrient removal performance, but greatly promoted the secretion of EPS. Remarkably, the granule structure was severely damaged under 100 mg/L PAN MPs. Moreover, microbial community analysis showed that phylum Proteobacteria played a dominant role in resistance to PAN MPs. Metabolic analysis further revealed that genes related to denitrification pathway (nasA, nirK, nirS and norB) and membrane transport were significantly inhibited under PAN MPs stress. This study may provide additional information on the treatment of microplastics wastewater using AGS.

[MIXed plastics biodegradation and UPcycling using microbial communities: the NSFC-EU 2019 project MIX-UP to help achieve "carbon neutrality"].

With the transformation and revolution of the global plastics recycling system, recycling and upcycling of mixed plastics waste not only reduces the carbon emissions of plastics during its life cycle, but also addresses its potential ecological and environmental hazards. This article summarizes an international cooperation project, "MIXed plastics biodegradation and UPcycling using microbial communities" (MIX-UP) which was funded by the National Natural Science Foundation of China and the European Union (NSFC-EU) in 2019. The consortium of MIX-UP consists of 14 partners from European Union and China. Focusing on the global issue of "plastics pollution", this Sino-European MIX-UP project took the mixed waste of petroleum-based plastics (PP, PE, PUR, PET and PS) and bio-based plastics (PLA and PHA) as starting materials for biotechnological conversion into value-added, sustainable biomaterials. MIX-UP has three subprojects: 1) identification of plastics biodegradation pathway and design & engineering of key degrading elements, 2) construction and functional regulation of microbial consortia/enzyme cocktails with high-efficiency for degradation of plastics mixtures, 3) strategy of design and utilization of plastics degradation products for production of high value materials. Through NSFC-EU complementary and cross-disciplinary cooperation, MIX-UP proposes the engineering of a new-to-nature biological route for upcycling, a low carbon and sustainable bio-treatment that is different from the traditional physico-chemical treatment, which will empower the recycling industry to a new dimension. The implementation of the project will not only help to promote innovation and development in the field of biotechnology in China, but also contribute to the achievement of China's carbon neutral goal.

Simultaneous qualitation and quantitation of natural trans-1,4-polyisoprene from Eucommia ulmoides Oliver by gel permeation chromatography (GPC).

Natural trans-1,4-polyisoprene (TPI) as a functional biomaterial has aroused great interest for rubber industrial product use. Here, we proposed a method that enables simultaneous analysis of the content and molecular-weight distribution (MWD) of natural TPI by gel permeation chromatography (GPC). The natural TPIs were collected from leaves, fruit coatings and bark of Eucommia ulmoides Oliver (E. ulmoides) through toluene extraction followed by ethanol purification. The results of TPI contents from leaves and fruit coatings were shown ca. 3.5% and 13.8%, respectively. Accordingly, limits of detection (LODs) of TPI were 0.58mg/mL from leaves and 0.47mg/mL from fruit coatings. The MWDs of TPI demonstrated a bimodal distribution from leaves, a unimodal distribution from bark, and a unimodal distribution with a tiny peak shoulder from fruit coatings. In real-life E. ulmoides analysis, the results from three independent methods (GPC, gravimetric method, and infrared spectroscopy) were obtained with good consistency.

Safe and efficient pH sensitive tumor targeting modified liposomes with minimal cytotoxicity.

Incorporating the pH-sensitivity of octylamine grafted poly aspartic acid (PASP) with the biocompatibility of liposomes, a novel pH sensitive drug delivery system, octylamine-graft-PASP (PASP-g-C8) modified liposomes (OPLPs), was obtained. Since hydrophobic chains have been grafted into PASP backbones, the octylamine chain could act as the "anchor" to implant onto liposomes. The structure of PASP-g-C8, involving long-chain and hydrophobic anchors can significantly enhance the stability of the drug carrier. The shortcoming of single PASP chain modified liposomes (PLPs), that cannot sustain a slow and controlled release especially in a physiological pH solution (resembling normal tissues of pH 7.4) is thus overcome. Drug release experiments were carried out and the result showed that OPLPs sustained a slow and steady release in comparison with PLPs in the physiological pH 7.4 environment. However, OPLPs can provide a fast release in subacid environment (pH 5.0 of resembled tumor tissues). The results of diameter analysis and zeta potential demonstrated that OPLPs presented a larger diameter and higher electronegativity. Furthermore, in the "chain-anchor" structure of PASP-g-C8, the degree of substitution (DS) of the "anchor" is a remarkable factor to alter the pH-sensitivity of OPLPs. The in vitro tumor inhibition and cell toxicity studies revealed that tumor cells treated with OPLPs survived only 35.0% after 48 h whereas normal cells survived 100% in the same condition. The pH sensitive OPLPs are promising tumor targeting drug delivery with high tumor inhibition and insignificant cytotoxicity.

Plate column biosorption of Cu(II) on membrane-type biosorbent (MBS) of Penicillium biomass: optimization using statistical design methods.

Based on the coupling of biosorption and membrane separation, a low cost membrane-type biosorbent (MBS) of Penicillium biomass was prepared. The surface morphology, pore properties and functional groups were studied via the characterization of MBS. Batch biosorption experiments indicated the maximum biosorption capacity of Cu(II) on MBS was 126.58 mg/g and about 90% of that on chitosan membrane. A plate column reactor filled with multi-layer of MBS was built for treatment of wastewater contaminated by Cu(II). The biosorption process factors were screened using Plackett-Burman design and three significant variables were selected for further optimization via response surface methodology (RSM) based on Box-Behnken model. A statistically second-order polynomial model was constructed with the error below 1.22%, on the basis of which the three-dimensional response surfaces were plotted. The prepared membrane-type biosorbent could be used successfully for 10 biosorption-desorption-regeneration cycles without decreasing its biosorption ability obviously.

Study of thermodynamics and dynamics of removing Cu(II) by biosorption membrane of Penicillium biomass.

Based on the integration of biosorption and membrane-separation, a novel biosorption membrane with good mechanical property was prepared by immobilizing Penicillium biomass with cross-linked chitosan on fabric. The ability of the low cost biosorption membrane to remove Cu(II) ions from a solution was studied through batch and continuous experiments. Langmuir adsorption isotherm models were found to accurately fit the batch experimental data (R(2) > 0.99) indicating that sorption was of monolayer-mode. The uptake of Cu(II) could reach 38 mg/g at its initial concentration of 200 mg/L in the solution. Continuous biosorption was investigated in a column and the effects of the height, flow rate and initial concentration of Cu(II) were studied. The Bed Depth Service Time model (BDST) was applied to simulate column adsorption data. The breakthrough time at different flow rates and initial concentrations was accurately predicted by the model (error < 8%). The uptake of Cu(II) could reach 38.3 mg/g at height 30 cm, flow rate 5 mL/min, initial concentration of Cu(II) 200 mg/L. The biosorption membrane was regenerated by washing with 0.05 mol/L solution of HCl, and breakthrough curves remained fairly unchanged after 10 cycles of adsorption-desorption.